1. Field of the Invention
The present invention relates to an image pickup unit provided with a lens unit and a chip-size-package image pickup chip and a method for manufacturing the image pickup unit.
2. Description of the Related Art
A chip size package (CSP) technique has been known in which a large number of semiconductor chips small in plan view dimensions are collectively produced by cutting and segmenting a semiconductor wafer in which a large number of semiconductor devices are formed on a first principal plane and external electrodes connected with each of the semiconductor devices via through wirings are formed on a second principal plane.
If an image pickup device such as a CCD is formed as a semiconductor device, the semiconductor chip is segmented after a glass wafer is joined to the first principal plane to allow producing the chip-size-package image pickup chip which is an image pickup device chip to which a transparent substrate is joined.
FIG. 1 is an exploded cross section view of an image pickup unit 110 disclosed in Japanese Patent Application Laid-Open Publication No. 2008-166939. The image pickup unit 110 includes an image pickup chip 140 in which a transparent substrate 130 is joined to an image pickup device chip 120 and a lens unit 170 composed of a lens barrel (an inner cylinder portion) 160 having an optical system (a lens) and an outer barrel (an outer cylinder portion) 150.
A center C of a light receiving portion 121 of the image pickup device chip 120 needs to be accurately aligned with an optical axis O of the optical system. In the image pickup unit 110, the optical system of the lens unit 170 is aligned with the image pickup device chip 120 such that the inner surface on the lower part of the outer barrel (a lens barrel) 150 is arranged to cover four sides of the image pickup chip 140 with no space therebetween.
That is, the image pickup unit 110 includes the image pickup device chip 120 having a rectangular shape in plan view, the transparent substrate 130 that is joined to the image pickup device chip 120 and equal in plan view dimensions to the image pickup device chip 120, and the lens unit 170 joined to the transparent substrate 130 with the center of the light receiving portion of the image pickup chip 140 aligned with the optical axis O.